In image forming apparatuses using an electrophotographic method such as copier, printer or the like, roller members provided with electrical conductivity are employed in electrophotographic processes such as developing, charging, transferring (providing toner, cleaning) and the like.
Conventionally, as electrically conductive rollers used as the developer rollers, charge rollers, transfer rollers (for providing toner, or cleaning) or the like, those having, as a basic structure, a structure in which an electrically conductive elastic layer comprising an electrically conductive rubber, polymeric elastomer, polymeric foam and/or the like provided with electrical conductivity by blending an electrically conductive agent on the periphery of a shaft is formed, and provided with one or more coating layers on the periphery of the elastic layer to obtain desired surface roughness, electrical conductivity, hardness and/or the like are used.
Here, although, for example, with the surface of an elastic layer made of urethane solid material, a desired surface roughness may be obtained by forming one coating layer on the surface, in the case of an elastic layer made of urethane foam, the surface roughness cannot be controlled unless the surface of the elastic layer is sealed with a water-based coating because a solvent-based coating causes problems such as melting of the surface of the elastic layer since the surface of the foam has open cells. Since there is a problem in, for example, that rough printed images are produced or a toner filming is caused when the surface roughness is not controlled, conventionally, in the case of the elastic layer made of urethane foam, a method of adjusting the surface roughness by dip coating with water-based coating for about 2 to 6 times before coating a solvent-based coating has been used.
As for improvements in electrically conductive rollers, for example, a charging member in which the vapor permeability and the degree of water swelling of a moisture-permeable polyurethane resin used for the surface layer are defined as predetermined amounts is disclosed in Patent Document 1.    Patent Document 1: Japanese Unexamined Patent Application Publication No. H6-301267 (claims, and the like)